1. Field of the Invention
The present invention generally relates to the field of liquid dispensers or applicators and, more particularly, to user-operable applicators that are configured to selectively dispense a liquid—of virtually any viscosity, including creams—from a storage reservoir and which exhibit particular resistance to leakage or other unintended discharges of stored liquid during periods of non-use, including shipping and transport from the manufacturing site to an ultimate purchaser or end-user.
2. Description of Related Art
Liquid dispensers and dispensing applicators are ubiquitous in the market place of today, providing an inexpensive and easily used vehicle for supplying a wide range of liquid-based products to the public. A common feature of such dispensers and applicators is the ability for the user to selectively effect a release or discharge of a typically internally-stored liquid through user-activation of a valving arrangement, commonly into a user's hand (for further transfer to another article or surface) or directly onto the intended surface or workpiece. Automatic closure of the valving arrangement, when the required user-activation effort has ended, to halt and prevent further unintended release of the stored liquid, is an attractive and, in some cases, important element of the functionality provided by such devices.
It will be appreciated that the usefulness and practicality of such liquid applicators and dispensers is significantly dependent on the ability of the valving arrangement to create and maintain an effect closure or seal against the release or leakage of stored liquid during times of nonuse. Many valving arrangements are spring-based closures in which a user-supplied force is applied against the spring to open the valve, and the return urgency drives the valve elements into a closed state when the user-supplied force is removed. Although a tighter or more leak resistant valve closure can be effected by utilizing a stronger spring, increases in the spring force also disadvantageously require more user-applied force to open the valve for each release of liquid and thus necessitate an unfortunate trade-off between user convenience and operational effectiveness.
A particular issue in avoiding unintended stored liquid releases and leakage in current liquid applicator and dispenser constructions arises during their shipping and transport—i.e., when the manufactured devices are shipped or otherwise transported to the retailer or ultimate end user. It is virtually certain that, at one or multiple points during such transport, the liquid-filled devices will be, at the very least, dropped, jostled and inverted, often resulting in unintended discharges or leakage of the stored liquid as the spring-based valving arrangement closure is unintendedly displaced.
Another cause of post-manufacture leakage arises due to the characteristics of some liquids commonly stored for dispensing from such devices. In their assembly, the final step is typically attachment to the applicator or dispensing assembly—i.e. the “working end” of the device—of a shell or container or the like which contains the liquid that the device is intended to dispense. Attachment (and liquid-tight securement) of the liquid-containing shell to the dispensing assembly, in which the valving arrangement is closed under the return urgency of a spring, often creates an overpressure condition within the liquid storage shell. With especially free-flowing, and volatile, liquids, the elevated pressure in the liquid storage reservoir will often result in releases of liquid through the closed valving arrangement, particularly during transport and most especially where, as is common, the devices are transported by air in low pressure or unpressurized cargo holds which still further increase the relative difference between the elevated pressure in the liquid storage container and the ambient atmosphere.